I bought a pair of Remchoke rifled choke tubes about 20 years ago, with the intention of doing something silly if I couldn't find a good SxS 12-bore Paradox or bore-gun.

The immediate problem was that the mouth of the forcing cone was way over-size, meaning that if a 12-bore barrel is .729 internally, the mouth of the forcing cone was perhaps .740 or more, and the rifled section was ~.729. This meant that the tubes I had intended to use (from defunct CBC single-barrel shotguns) would have needed to be reamed out by at least 10 thou full-length to allow the forcing cone to work as Colonel Fosbery intended!

So either Remington pumpies and semi-autos have seriously oversized 12-bore barrels, or Remington were so risk-averse with these removable chokes that they virtually defeated the purpose.

Thankfully I acquired the Holloway Paradox in time to prevent the silliness. I would have procrastinated for a looong time anyway...